In a manufacturing process of a semiconductor device, some of multiple regions formed of different semiconductor materials are selectively etched. By way of example, with respect to a first region formed of silicon in a target object, a second region formed of silicon oxide in the target object is selectively etched. Such an etching method is described in, for example, Japanese Patent Laid-open Publication No. 2010-098220 (Patent Document 1).
To be specific, Patent Document 1 describes a method of selectively etching a region formed of silicon oxide with plasma of a processing gas containing fluorocarbon such as C4F6 and O2 with respect to a region formed of silicon. Further, in the same document, it is described that SF6 is used instead of O2.
In the etching method described in the Patent Document 1, the region formed of the silicon oxide is etched with active species from the fluorocarbon while protecting the region formed of the silicon by a CF-based deposit generated from fluorocarbon in the processing gas. To be specific, the fluorocarbon active species (hereinafter, referred to as “CF active species”) are deposited on a target object, and the silicon oxide is etched through a sputtering effect of ions in the CF active species. To be more specific, oxygen contained in the silicon oxide are bonded to carbon contained in the ions of the fluorocarbon, so that the oxygen are separated from the silicon oxide. Further, fluorine generated when the carbon is separated from the ions of the fluorocarbon is bonded to silicon generated when the oxygen is separated. Thus, the silicon oxide is etched.
Patent Document 1: Japanese Patent Laid-open Publication No. 2010-098220
In the conventional etching method describe above, when the region formed of the silicon oxide is etched, the region formed of the silicon are also etched. Therefore, there has been demanded a technique of suppressing the region formed of the silicon from being etched and also improving etching selectivity of the region formed of the silicon oxide with respect to the region formed of the silicon.